This disclosure generally relates to an electronic bypass system, and, more particularly to an electronic bypass system for facilitating and monitoring bypasses to plant interlock systems.
Manufacturing plants typically utilize several types of plant safety systems such as alarms, safety trips, interlocks, and pressure relieving systems. Plant interlock systems may be used to enforce a fixed sequence of operations, for example, during a plant start-up or shutdown process. During plant start-up, interlocks are often used to provide safety protection by requiring that certain permissible conditions exist before proceeding to a next stage of the process. Interlock systems are inserted into the process to prevent operations from departing from the fixed sequence. An interlock system is a group of devices arranged to sense an operating limit or off-limit condition, or an improper sequence of events, and is used to shut down the process or prevent the process from proceeding if any are detected. An interlock system often includes various alarms and safety trips.
Safety interlocks are also applied in locking and unlocking closing valves in a chemical plant. A closing valve provided with an interlock system may be locked in the closed position (locked closed system) or locked in an open position (locked open system). By providing closing valves with an interlock, undesired operation thereof can be prevented. It is also possible, using the locking mechanism on a number of different closing valves, to ensure a correct, predetermined sequence of closing or opening of the closing valves that may be used, for example, to prevent hazardous situations.
Safety interlocks may be bypassed temporarily for a variety of reasons, such as system maintenance. A typical interlock bypass procedure includes an operation supervisor filling in a bypass request form and handing it to a plant superintendent. The plant superintendent then reviews the request and approves the bypass for a specified time period (e.g., twenty-four hours). The approved bypass request form is then handed back to the operation supervisor who takes the appropriate action to bypass the safety interlock. This current manual method of implementing interlock bypassing is often time consuming and it is difficult to get a view of the current status of safety interlocks and bypass activities (bypasses in place, bypasses requested, etc.) across one or more plant locations.
There continues to be a need in the art for efficient methods to facilitate and monitor the bypass of safety interlocks.